[FFmpeg-devel] [PATCH] lavc/libx264: add a warning when using qscale

[James Darnley]

On 2014-03-22 02:01, Lou Logan wrote:
> On Fri, Mar 21, 2014, at 04:24 PM, James Darnley wrote:
>> This addresses ticket #3238.
>> ---
>>  libavcodec/libx264.c |    3 +++
>>  1 files changed, 3 insertions(+), 0 deletions(-)
>>
>> diff --git a/libavcodec/libx264.c b/libavcodec/libx264.c
>> index 6007630..644a582 100644
>> --- a/libavcodec/libx264.c
>> +++ b/libavcodec/libx264.c
>> @@ -330,6 +330,9 @@ static av_cold int X264_init(AVCodecContext *avctx)
>>      X264Context *x4 = avctx->priv_data;
>>      int sw,sh;
>>  
>> +    if (avctx->global_quality > 0)
>> +        av_log(avctx, AV_LOG_WARNING, "-qscale is ignored, -crf is
>> preferred.\n");
> 
> Thanks for the patch. Just two nits to consider or discard at your
> leisure:
> 
> Nit 1: Although [libx264 @ address] will precede the warning (right?)
> some users may skip over that part (possibly due to a color difference
> or the length of the address), and therefore could assume that the
> message applies to all encoders.

You might have a point.  Users seem able to ignore everything except the
last line printed by a program.  They probably wouldn't see this message
anyway.  So I would leave it as is.

Unrelated but, I'm not a big fan of different components getting
different colours.

> Nit 2: s/preferred/recommended/

I agree.

> How about: -qscale is ignored by this encoder, -crf is recommended

If you or whoever applies this wants to draw attention to the encoder
feel free.  I will send an updated patch in just a moment.

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